The present invention relates to an optical information recording medium usable for writing and reading with a light beam such as laser.
Recently, various optical information recording media for recording information and regenerating the recorded information by irradiating a light beam have been studied, and have been gradually produced into merchandise.
An optical information recording medium is usually composed of a disk-like substrate having a light reflective recording layer thereon. Since the recording layer easily deteriorates by the action of air or is damaged by abrasion, it has been tried to place a protective layer on the recording layer to prevent these deteriorations. For example, Japanese Patent Application Laid Open Nos. 57-60542 and 57-66541 disclose these techniques, but various properties such as sensitivity, C/N, contrast and the like are lowered and a satisfactory product can not be obtained up to now.
Another conventional method for protecting a recording layer uses a "sandwich structure". This comprises two recording media having the above mentioned structure (two recording layers are not always necessary) and sealing two recording layers in the inside by having the two layers face toward each other and having intervening air therebetween. This structure has a merit of avoiding damage by direct abrasion, but has a demerit of a weak mechanical strength due to the sandwich structure.